Materials Vector vs Scalar

Hi everyone.
I’m a newb and have a bit of a question.
I’m learning about materials and following tutorials, during which I created a vector and scalar parameters to help create a material instance.
But I don’t understand why we chose the vector and scalar parameters.
Are they interchangeable ie create 2 vector parameters instead of a scalar.
What is the difference between them and where does each one get used.

Thanks for any help.

A vector parameter is basically the same as having four scalar paramters.